Different kinds of edge-type lighting devices where light sources are disposed on edges of light guide plates have been proposed (for example, refer to Patent document 1).
FIG. 11 is a sectional view illustrating an embodiment of a conventional structure of an edge-type lighting device. In the drawing, reference numeral 202 denotes a light guide plate made of a transparent material, and reference numeral 203 denotes light sources which are disposed facing each other on respective edges of the light guide plate 202 and emit light L1 into the light guide plate 202. The lighting device is configured such that light L1 that is emitted from the light sources 203 and enters the light guide plate 202 is emitted from a front surface of the light guide plate 202 (see reference numeral L2). In the edge-type lighting device having the above-mentioned construction, the light sources 203 can be disposed on the edges of the light guide plate 202 rather than on a rear surface of the light guide plate 202. Therefore, the edge-type lighting device can be markedly reduced in thickness. Such an edge-type lighting device is mounted to a ceiling, a sidewall, etc. of a room or the like.